The Dawn spacecraft has returned the sharpest ever images seen of Ceres ahead of its historic rendezvous with the dwarf planet.

The images were taken from 147,000 miles (237,000 km) away on January 25, and represent a new milestone for a spacecraft that soon will become the first human-made probe to visit the 'Death Star' planet.

At 43 pixels wide, the images are more than 30 per cent higher in resolution than those taken by Nasa's Hubble Telescope in 2003 and 2004 at a distance of over 150 million miles.

The images that make up this animation were taken from 147,000 miles (237,000km) away on January 25 as Dawn edges closer to its target in March

The dwarf planet has been likened to the death Star from the hit film Star Wards

'We know so little about our vast solar system, but thanks to economical missions like Dawn, those mysteries are being solved,' said Jim Green, Planetary Science Division Director at Nasa.

The new Dawn images come on the heels of initial navigation images taken January 13 that reveal an 'alien' white spot on the dwarf planet and the suggestion of craters.

While Nasa has not provided an explanation, scientists suggest it may be a frozen pool of ice at the bottom of a crater that reflects light.

We can confirm that it is something on Ceres that reflects more sunlight, but what that is remains a mystery,' Marc Rayman, mission director and chief engineer for the Dawn mission, told Space.com

Over the next weeks, Dawn will provide increasingly sharper images of the icy world, leading up to the spacecraft's capture into orbit around Ceres on March 6.

'We know so much about the solar system and yet so little about dwarf planet Ceres.

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At 43 pixels wide, the images are more than 30 per cent higher in resolution than those taken by Nasa's Hubble Space Telescope in 2003 and 2004 at a distance of over 150 million miles

The 'alien' mark can be clearly seen in the latest images the icy world as the Dawn probe hurtles its way towards a rendezvous on March 6

As the Dawn spacecraft closes in on Ceres, new images have emerged showing the solar system's largest asteroid at 27 pixels across - three times better than the images taken in early December. This GIF shows bright and dark features

On the left is a processed image, taken January 13. It hints at craters on the surface of Ceres. Dawn's framing camera took this image at 238,000 miles (383,000km) from Ceres. On the right, is a zoomed-in raw image

Ceres is 590 miles (950 km) across and was discovered in 1801. In January, researchers discovered that water was gushing from its surface at a rate of 13lb (6kg) per second.

'Now, finally, we have a spacecraft on the verge of unveiling this mysterious, alien world,' Dawn mission director and chief engineer Marc Rayman, of Nasa's Jet Propulsion Laboratory in Pasadena, California said.

'Soon it will reveal myriad secrets Ceres has held since the dawn of the solar system.'

Observations by the European Space Agency's Herschel telescope suggested they could be coming from geysers or ice volcanoes.

Ceres orbits the sun in the asteroid belt between Mars and Jupiter and is very similar to Jupiter's moon Europa and Saturn's moon Enceladus - both considered potential sources for harbouring life.

Ceres is the bright spot in the centre of the image. Because the dwarf planet is much brighter than the stars in the background, the camera team selected a long exposure time to make the stars visible. The long exposure made Ceres appear overexposed, and exaggerated its size A cropped, magnified view of Ceres appears in the inset image at lower left

Dawn will be captured into Ceres' orbit in March, marking the first visit to a dwarf planet by a spacecraft (artist's impression pictured)

THE MYSTERIOUS WORLD OF CERES

Ceres is the closest dwarf planet to the sun and is located in the asteroid belt, making it the only dwarf planet in the inner solar system.

Ceres is the smallest of the bodies currently classified as a 'dwarf planet'.

Scientists think Ceres may have an ocean and possibly an atmosphere.

It lies less than three times as far as Earth from the sun - close enough to feel the warmth of the star allowing ice to melt and reform.

Nasa's Dawn spacecraft has been making its way to Ceres from the asteroid Vesta since September 2012. It is due to land next year.

There is high interest in the mission because Ceres is one possible destination for human colonisation given its abundance of ice, water, and minerals.

Dr Michael Kuppers, of the Esa's lab in Villanueva de la Canada in Spain said: 'Although ground and space-based observations may further map the behaviour of Ceres over its orbit the Dawn spacecraft mission arriving to orbit Ceres in early 2015 is expected to be key in providing a long-term follow-up on the water outgassing behaviour of Ceres.'

The presence and abundance of water in bodies like Ceres could have relevance for the origin of life on Earth and the large-scale migration of planets such as Jupiter.

One scenario suggests as the giant planets migrated they disturbed populations of small rocky and icy asteroids and comets which hit the early Earth and Moon - delivering organic molecules and water to Earth.

Ceres is twice the size of Saturn's geyser-spouting moon Enceladus which is suspected of having liquid water beneath its surface.

It lies less than three times as far as Earth from the sun - close enough to feel the warmth of the star allowing ice to melt and reform.

Since launching in 2007, Dawn has already visited Vesta, a giant protoplanet currently located 104 million miles (168 million km) away from Ceres.

The distance between Vesta and Ceres is greater than the distance between the Earth and the sun.

During its 14 months in orbit around Vesta, the spacecraft delivered unprecedented scientific insights, including images of its cratered surface and important clues about its geological history.

Vesta and Ceres are the two most massive bodies in the main asteroid belt.

The image was taken as part of a final calibration of the science camera before Dawn's arrival. On December 1, Ceres was about nine pixels in diameter - nearly perfect for this calibration

Ceres is 590 miles (950 km) across and was discovered in 1801. In January, researchers discovered that water was gushing from its surface